Rail flaw detector mechanism



.Filed March 9, 1935 2/ N www mw NN m o o am a @N wf uw l K C. L/ n U f@ m a H meg - electromagnetic held will atented Mar. 23, 193W UNITED STATES PATEN oFFic.

'ifla'ldll RAIL FLAW DETECTOR MECHANISM Harcourt C. Drake, Hempstead, N. Y., assignor to Sperry Products, Inc., poration of New Yorh Brooklyn, N. Y., a cor- Application March 9, 1935, Serial No.1d,ll4l3 i claims. (el. iis-ree) This invention relates to rail flaw detecting apparatus of the type employed in the Sperry rail flaw detector ca Such flaw detection apparatus comprises passing of a heavy current through an electrical' conductor to be tested so as to establish an electromagnetic field surrounding the conductor and then movinga pair of opposed intact brushes and leaves the conductor by a second ACA set of brushes, both sets of brushes being carried by a carriage which supports the detector mechanism between the two sets of brushes. It has been found that it takes some time after the curfor the molecules to themselves `with the proper polarity relarent enters the conductor align tive to the polarity of the energizing current, and` for this reason the said Sperry detector cars carry mechanism for preenerglizing the rail. Such preenergizing arrangement is disclosed in applicants Patent No. 1,944,930 granted January 30, 1934.

Reference to the said patent discloses that in order to obtain the desirable eect of preenergization it was necessary to employ a third set of brushespositioned ahead of the original inlet and outlet current brushes and supplied with current from an auxiliary generator. The present invention has for its principal object the provision of means whereby the same leffect of preenergization may be obtained at all times by theV use of but a single generator instead of a. main generator and an auxiliary generator as disclosed in the said patent.

Further objects and advantages of this invention will become apparent in the following detailed description thereof:

In the accompanying drawing,

Fig. 1 is a side elevation of a Sperry rail ilaw detector car showing by a wiring diagram applicants invention applied thereto.

Fig. 2 is a wiring diagram disclosing the form of preenerglzing `arrangement heretofore employed. j

Referrignagjto Fig. 1 of the drawing, there is disclosed Sperry rail naw detector car com prising the car bodyV lll within which is mounted may be adapted to a generator G adapted to supply current to the rail to establish an electromagnetic field surrounding the same. The current from generator G may be passed into and out of the rail by means of sets of brushes il and I2. Said set'of brushes Iii and an auxiliaryset of brushes [It may be carried by a current brush carriage it, said carriage being supported on 'the car body lll by means such as cables it and springs, not shown,' which normally maintain the current brush carriage in raised or ineective position.

When itis desired to lower said carriage into engagement with the rail, lfluid pressure such'as compressed air is supplied to cylinders il to depress piston-rods it, said piston-rods being connected to the-current brush carriage so that said carriage is lowered against the action of the retractile springs. The current brush carriage ride along the rails on means such as anged wheels it. The set of brushes ll may be raised by means of a cable it and a spring, not shown, and may be lowered by supplying the compressed air to an additional cylinder il" to depress piston-rod it. The source of compressed air is connected to said cylinders il and lll' so that all of said brushes are raised and lowered simultaneously.

Uurrent is normally supplied from the generator G to front brushes il through the rail R to l rear brushes-li and returned to the generator.

electromagnetic eld surrounding the rail is thus built up and said field is uniform as long as there are no naws. When aws occur there is a distortion of the electromagnetic eld in the region of the flaw and such distortions are designed to be detected `by induction means which may comprise a pair of opposed induction coils 2d supported in a housing 2l carried by a detector carriage 22 which is designed to be supported on the current brush carriage Id lfor movement independent thereof by means such as loose-litting bolts 23 and springs 24 consti- Qtuting limited universal joints. The detector carripge 22 may be supported on the rail surface by means such as rollers 2b, and the current brush carriage may be supported on the rail by means such -as ilanged wheels I 9. It will now be seen that as the car travels along the rail R the inductive means are maintained a constant distance above the rail surface and will normally cut a constant number of lines of force.

When a region of ilaw is encountered, one of the coils will cut a diierent number of lines of force and there will be generated a differential E. M. F.

which, after being amplied, may be caused to Cil -is supplied by generator operate indicating means such as' pens operating on a moving chart and rail marking means such as a paint gun.

By yreference to Fig. 1 it will be seen that the, detector carriage 22 is positioned as far removed from the lfront current brushes II as the car construction will permit. This is desirable because, as stated in the introduction to this speciiication, a certain time elapses before the current passing through the rail can align the molecules of the rail so that their poles are homogeneously arranged. This has been found to facilitate greatly the detection of flaws. The positioning of the front current brushes II so far ahead of the rear brushes I2 creates certain dimculties which will be apparent from a study of Fig. 1 wherein an insulated joint is shown at J. This means that as soon as the front current brushes II have passed the insulation of joint J, no current is passing through rail R and the flaw responsive means is ineffective to discover any iiaws in that portion of the rail between the point where the detector carriage'is positioned when brush II passes joint J and .the said joint. This is a substantial distance and equivalent to almost the car length.

One solution of the above difiiculty is disclosed in the said Drake Patent No. 1,934,930 and is shown in Fig. 2. In this form of the invention, an auxiliary generator G' is provided for performing the preenergizing function between brushes II and brushes I3. The normal current G between brushes I3 and brushes I2. Thus, when front brushes II have passed an insulated joint J or a joint of high resistance whichcauses a sharp drop in the current passing over brushes II to brushes I2, the flaw responsive mechanism is not affected because generator' G continues to supply current between brushes I3 and brushes I2. This solution of the problem, however, requires-'the use of an auxiliary generator G and it is the object of the present invention to perform the "same function with but a single generator.

This solution of the problem is disclosedv in Fig. 1 wherein the current normally is supplied by generator G to front brushes II and passes to rear brushes I2 before returningtc the generator. When, however, the brushes II pass an insulated joint J or joint of high resistance which causes the current to drop between brushes II and brushes I2, I provide means for rendering effective a flow of current from generator G through auxiliary front brushes I3 to rear brushes I2 and return to the generator. Since auxiliary front brushes I3 are close to the naw responsive means 20, full current will pass between brushes I3 and brushes I2 until s aid brushes I3 pass the joint J, at which time the haw responsive mechanism will have reached the joint bar B in which region no testing is performed in any case.A f I accomplish this result by placing in the circuit from generator G through front brushes II and rear brushes I2, a resistance S and an electromagnet 30 in parallel with the circuit through the brushes I I. Said resistance is of such magnitude that -normally insui'ncient current passes through inagnet 30 to enable it to attract an armature 3l against the action of a retractile spring 32, and the major portion of the current passes through brushes II. However, when front brushes II pass an insulated joint or joint of high resistance all of the current is diverted through resistance' S and magnet 30 sothat sumcient current passes through the lmagnet to enable it to attract arma- "I2, and return to generator.

ture 3| and close a set of contacts 33. The closing of said contacts .33 closes a normally ineffective auxiliary circuit from generator G through said contacts, the armature 3 I brushes I3, brushes 'I'he contacts 33 also short-circuit resistance S so that the full current flows through brushes I3.

Since a certain amount of current tiows through resistance S and magnet 33 when contacts 33 are open, there is current flowing through the rail in the region of the detector coils at all times, even in that interval when brushes II have just passed the joint J and before contacts 33 have closed. When brushes I3l have passed the joint the circuit through magnet 3l is interrupted and the current therein falls to such extent that retractile spring 32 opens the contacts 33. As soon as brushes I2 have passed joint J the current is immediately ready to ilow from brushes Il to brushes I2 by reason of the open contacts 33 which causes the main portion of the current to flow through brushes I I. y

In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my invention, together with the apparatus which I now consider to represent the` best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other equivalent means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these. may be altered and others omitted without interfering with the more general results outlined, and the invention extends to such use.

Having described my invention, what I claim and desire to secure by Letters Patent is: 1. In a rail ilaw detector car, a source of electrical energy, means for establishing a circuit from said source through the rail, flaw responsive means cooperating with the energized portion of the rail, a normally ineffective auxiliary circuit including said source and extending through the rail in the region under test, and means whereby said auxiliary circuit is rendered effective when the current in said iirst circuit drops to a predetermined degree.

2. In a rail flaw detector car, a source of electrical energy, a main circuit including said source and front brushes and rear brushes for passing current from said lsource through the rail, flaw responsive means positioned nearer to the rear brushes than to the iront brushes.' a normally ineffective auxiliary circuit from said source and extending through the rail in the region of said normally ineffective auxiliary circuit from said source and extending through the rail in the region of said flaw responsive means, said auxiliary circuit including auxiliarybrushes positioned between said front and said rear brushes, and means whereby said auxiliary circuit .is rendered eiective when the current between said front and rear brushes drops to a predetermined degree.

'V trical energy,

l 4. In a rail naw detector car, a source of electrical energy, a main circuit including said source and front brushes and rear brushes for paing current from said source through the rail, aw responsive means positioned nearer to the rear brushes than to the front brushes, a normally ineffective auxiliary circuit including said source and extending through the rail in the region of said aw responsive means, said auxiliary circuit including auxiliary front brushes positioned closely adjacent said responsive means, and means whereby said auxiliary circuit is rendered effective when the current between said rst named' front brushes and said rear brushes drops to a predetermined degree.

5. In a rail aw detector car, a source of eleca main circuit including said source and front brushes and rear brushes for passing current from said source through the rail, flaw responsive means positioned nearer to the rear brushes than to the front brushes, a normally ineiective auxiliary circuit through the rail in the region of said flaw responsive means, and means whereby said auxiliary circuit is rendered effective when the current between said front and rear brushes drops to a. predetermined degree, said last-named means comprising a shunt circuit including a magnet, said auxiliary circuit including a pair of contacts and means normally maintaining said contacts open to render said auxiliary circuit ineffective, means whereby said magnet closes said contacts when the current through said magnet exceeds a predetermined quantity, and a resistance in said shunt circuit for maintaining the current through said magnet below said predetermined quantity as long as the current in said main circuit exceeds a predetermined quantity.

6. YIn a rail flaw detector car, a source of electrical energy, a main circuit including said source and front brushes and rear brushes for passing current from said source through the rail, ilaw responsive means positioned nearer to the rear brushes than to the front brushes, a normally ineffective auxiliary circuit through the rail in the region of said aw responsive means, and

' means whereby said auxiliary circuit is rendered eiiective when the current between said frontand rear brushes drops to a predetermined degree, said last-named means comprising a shunt circuit includinga magnet, 'said auxiliary circuit including said magnet, a pair of contacts and means normally maintaining said contacts open to render said auxiliary circuit ineffective, means whereby said magnet closes said contacts when the current through said magnet exceeds a predetermined quantity, a resistance in said shunt circuit for maintaining the current through said magnet below saidv predetermined quantity as long as the current in said main circuit exceeds a predetermined quantity, and means whereby closing of said contacts to render said' auxiliary circuit eiective short-circuits said resistance.

7. In a rail ilaw detector carra source of electrical energy, a main circuit including said source and front brushes and rear brushes for passing current from said source through the rail, flaw responsive means positioned nearer to the rear brushes than to the front brushes, a normally ineiective .auxiliary circuit through the rail in the region of said aw responsive means, and means whereby said auxiliary circuit is rendered effective when the current between said front and rear brushes drops to a predetermined degree, said last-named means comprising a shunt circuit including a magnet and auxiliary brushes positioned between said front and rear brushes, said auxiliary circuit including said magnet, said auxiliary brushes, a and means normally maintaining said contacts open to render said auxiliary circuit ineffective, means whereby said magnet closes said contacts when the current through said magnet exceeds a predetermined quantity and a resistance in said shunt circuit for maintaining the current through said magnet below said predetermined quantity as long as the current between said front and rear brushes exceeds a predetermined quantity.

HARCOURT C. DRAKE.

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pair of contacts, 

